南黄海海相油气地震勘探难点分析与对策建议

南黄海海相残留盆地广泛分布中古生代碳酸盐岩地层。盆地的油气勘探仍处于前景调查评价阶段。分析了研究区特殊地震地质条件造成的地震采集和处理所面临的诸多难点:地下地质构造复杂造成地震波场传播路径复杂多变,碳酸盐岩高速屏蔽层使得地震波向下传播的能量微弱,以及海洋作业环境等。针对地震资料多次波发育、深部目标层反射能量弱、信噪比低、成像精度低、资料品质差等困难和状况,提出了相应的勘探策略,如:加强理论模拟研究;采用多层震源延迟激发技术和"长排列、上下缆"的立体宽线接收技术,以拓宽频带、提高深部目标层反射能量;采用多次波压制技术以突出中深层弱反射;采用针对长排列的各向异性速度分析和各向异性叠前时间偏移以提高复杂构造成像能力等。     

Radon变换多次波压制方法及应用研究

多次波在地震资料中是普遍存在的。Radon变换是现行商业地震资料多次波压制处理软件应用最多的模块之一。这里在详细阐述Radon变换基本原理和离散采样计算的基础上,给出了理论模拟地震数据的多次波压制算法和计算结果。进而将Radon变换多次波压制方法应用于松辽盆地地震资料处理中,在对实际的CRP道集合理设计滤波切除函数后,应用本文的Radon变换算法,得到多次波压制的地震剖面。对比多次波压制前、后的叠前时间偏移地震剖面,压制多次波后地震剖面的信噪比很高,地质构造特征清晰,可应用于后续的地质构造解释,地震属性提取和油气储层预测。该方法的计算效率较高,算法易于实现。理论和实际地震数据的多次波压制结果表明,该算法具有高精度和实用性强的特点。     

面向海洋剩余多次波衰减方法的研究

随着近几年长排列大容量震源地震勘探技术的广泛采用,勘探目标逐渐趋向于中深部地层,使其成为目前研究南海深部构造的主要研究手段之一。但由于一些剩余多次波的影响,一直成为中深层成像与解释的瓶颈。针对南海某海域的实际资料,在采用SRME技术与高精度Radon变换等常规衰减技术的基础上,仍会存在一些残余多次波,主要为崎岖海底或者复杂构造引起的绕射多次波。针对剩余多次波的特点,在不同的频带范围内,通过径向中值滤波评估得到不同的"含信因子"用于异常噪音的衰减,同时为了提高数据保真度,引入逐步衰减的处理机制,层层检验衰减效果,最后结果表明,数据中剩余多次波能量被较好压制,提高了中深层的信噪比,基底以下的深部构造得到了较好地展示。     

鄂尔多斯盆地低信噪比复杂地区检波器组合方法分析

在鄂尔多斯盆地西北部,低信噪比复杂地区存在严重的随机干扰,这导致该区地震资料信噪比很低。在不提高覆盖次数情况下,针对该区造成地震资料信噪比低的严重随机干扰问题,开展检波器组合压制随机干扰的方法研究。研究了随机干扰对动静校正量准确求取的影响,检波器组合对干扰波的压制作用,组内高差和组合基距对地震采集资料高频的影响,对比分析检波器组内距对随机干扰的衰减效果。研究结果表明:在盆地低信噪比复杂地区,野外检波器组合重点压制严重的随机干扰波,提高地震资料信噪比;小于1 m的检波器组内高差对该区地震采集资料110 Hz以下高频成分影响有限,小于13 m组合基距对中、深目的层地震资料70 Hz以内频率影响有限;理论计算和试验资料综合确定的随机干扰半径为1.7~2.0 m,大于随机干扰半径的检波器组合内距能有效压制随机干扰波,其中组内距3 m比较稳定;以上参数确定的检波器组合接收方法压制随机干扰波后,所得到的地震单炮记录相比单点接收、高覆盖次数压制随机干扰波所得到的资料在70 Hz有限频带内更能提高信噪比、频率,而且成本相对低。该结果在鄂尔多斯盆地低信噪比复杂地区地震勘探野外采集中具有指导作用。      

微屈多次波正演模拟及其在中原油田深层地震资料解释中的应用

对微屈多次波的压制或利用是地震资料处理、解释中的一个难题。正演模拟是压制或利用微屈多次波的基础。笔者利用层状介质非线性模型理论,发展了一种正演模拟微屈多次波的方法。利用这一方法在中原油田深层地震资料解释中作了初步应用,取得了一些有用的成果。该方法也可以在地震子波分析处理和提高地震资料分辨率中发挥作用。     

基于经验低秩表示的自适应多次波减去方法

多次波压制一直是海洋地震数据处理的研究重点,SRME（surface-related multiple elimination）方法通过多次波预测、自适应减去两个步骤实现多次波压制,具有压制精度高、模型依赖度低等优点,是工业界广泛采用的方法。但是常规减去方法在一次波、多次波交叉位置易出现一次波损伤、多次波残留等现象,进而增加后续地震处理、解释的难度。本文在前人研究的基础上,提出了基于经验低秩表示的自适应多次波减去方法。首先,采用经验低秩表示方法,将地震数据自适应地分解为信噪比高、倾角单一、同相轴相位圆滑的低秩倾角分量,简化地震数据倾角成分的复杂程度,以优化低秩表示过程中局部窗口的参数选择问题;然后,在不同低秩倾角分量中分别采用基于能量最小原则的匹配减去方法,避免匹配过程出现同相轴交叉,并重构各分量,在保证计算效率的前提下提升多次波压制效果。针对理论数据和实际数据进行了有效性测试,本文方法在多次波压制结果和保幅性两方面优于传统方法,并采用抗噪性测试证明了该方法的鲁棒性。     

南黄海中部浅水区多次波衰减技术及其效果分析

在浅水区,由于水深较浅,缺少近偏移距的海底反射信号,采用常规SRME方法和预测反褶积不能有效地衰减海底相关多次波。笔者采用DWD+SRME组合法来衰减海底相关多次波,其中DWD方法用来衰减与海底相关的短周期多次波,SRME方法压制自由表面相关的长周期多次波,另外运用Radon变换去除层间多次波。结果表明,运用DWD+SRME组合法压制海底相关多次波效果较好,并且没有损害浅层的有效反射信号,采用Radon变换使层间多次波得到了良好的压制,深部有效反射信号逐步体现。因此,对于浅水区低信噪比地震资料,采用DWD+SRME组合方法和Radon域去多次,是比较可行的去多次波方法。     

南海南部深水区低品质地震资料处理关键技术

中国南海南部深水区勘探前景广阔,但地震资料极其稀少且品质低。针对中国南海南部深水某区块原始地震资料采集于20世纪70年代、无导航文本、海底记录时间不确定、缺道严重及电缆短的品质限制,造成该区仅有的纸质成果剖面上多次波严重、信噪比低、地层构造形态模糊问题,探索出一套适合于工区地震资料处理的关键技术:采用导航重构技术解决无导航文本问题;采用自相关海底拾取技术解决海底记录不确定问题;采用限频F-K域插值技术解决缺道问题;采用组合法压制多次波技术解决因电缆短多次波难压制问题。最后处理效果表明关键技术的应用使该区地震资料处理取得了预期效果。这些技术成果不仅为我国南海南部深水的油气勘探提供较可靠的地震资料,同时为类似低品质地震资料的处理提供了可借鉴的思路和技术。     

南海北部陆坡区多次波组合压制技术

南海北部陆坡区大部分为深水崎岖海底地貌,各种类型多次波十分发育,多次波的辨识和压制历来是该区地震资料处理的难点和重点。选取适合的多次波压制技术方法是获得高质量成像地震剖面的关键。通过对东西向排列的三条测线原始资料中多次波的发育情况研究,分析了该区多种类型多次波的特点,组合应用τ-p域预测反褶积、自由表面多次波衰减(SRME)、高精度Radon变换和分频能量衰减法,对各种多次波进行有效压制,使叠加效果和质量明显得到改善,中、深层反射波组特征清楚,易于辨识和解释。     

南海南部深水多次波模拟分析与压制处理

南海南部陆缘构造复杂多变,海底崎岖不平,造成该区多道地震资料多次波十分发育且混杂复杂绕射波。为了识别深层有效反射信息、压制多次波,首先通过正演模拟分析深水条件下多次波的传播规律和特征,然后对复杂理论Pluto模型进行详细处理并试验了几种典型多次波压制方法,寻找到一套有效的多次波压制处理思路:通过表面相关多次波衰减(SRME)法降低多次波能量级别,运用τ-p域预测反褶积压制周期规律的近中道多次波,再在此基础上灵活运用高分辨率抛物线Radon变换对共反射点道集(CRP)进行中远道多次波压制。理论模型和礼乐盆地海区的实际资料处理结果表明,该方法能够较大程度上压制深水资料多次波并增强对深部有效信息的识别。     

The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures,South Wales,UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia)

Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.     

Définition d'une limite multicritère ; stratigraphie du passage Campanien–Maastrichtien du site géologique de Tercis (Landes,SW France)Definition of a multi-criteria boundary; stratigraphy of the Campanian–Maastrichtian interval of the geological site at Tercis (Landes,SW France)

Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414.     

The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts

The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H₂O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H₂O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.     

Quaternary stresses revealed by calcite twinning inversion: insights from observations in the Savonnières underground quarry (eastern France)

Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ₁ roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).     

HYDROGEOLOGY

正20141756 Chen Ruige(Mathematical College,China University of Geosciences,Beijing100083,China);Zhou Xun Numerical Simulation of Groundwater Level Fluctuation in a Coastal Confined Aquifer with Sloping Initial Groundwater Level Induced by the Tide(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,32(7),2013,p.1099-1104,6 illus.,16 refs.) Key words:confined water,groundwater level     

METAMORPHIC PETROLOGY

正20141408 Cai Jia(Institute of Geology,Chinese Academy of Geological Sciences,Beijing100037,China);Liu Fulai Petrogenesis and Metamorphic P-T Conditions of Garnet-Spinel-Biotitebearing Paragneiss in Danangou Area,Daqingshan-Wulashan Metamorphic Complex Belt(Acta Petrologica Sinica,ISSN1000-0569,CN11-1922/P,29(7),     

SERIALS

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GEOPHYSICAL EXPLORATION

正20142386An Guoying(China Aero Geophysical Survey and Remote Sensing Center for Land and Resources,Beijing 100083,China)Application of Satellite Remote Sensing in Regional Hydrogeological Investigation:Taking Cenozoic Strata in Wenquan Sheet(1∶250 000)of Karakoram Range as an Example(Geosci-     

QUATERNARY GEOLOGY & GEOMORPHOLOGY

正20141016An Chengbang(Key Laboratory of Western China’s Environmental Systems,Ministry of Education,Lanzhou University,Lanzhou 730000,China);Zhao Yongtao Lake Records during the Last Glacial Maximum from Xinjiang,NW China and Their Climatic Impli-     

PETROLEUM GEOLOGY

正20141538 Cao Qing(School of Earth Sciences and Engineering,Xi’an Petroleum University,Xi’an 710065,China);Zhao Jingzhou Characteristics and Significance of Fluid Inclusions from Majiagou Formation,Yichuan Huangling Area,Ordos Basin(Advances in Earth Science,ISSN1001-8166,CN62-1091/P,28(7),2013,p.819-828,7 illus.,3 tables,43 refs.)